In 2010, it was safe to assume that the Syracuse University defense would be good.

The unit had 11 players who had started in games the season before, and only two positions — nose tackle and strong-side linebacker — had new faces.

Things are different this year, as defensive coordinator Scott Shafer has new starters at five positions.

Shafer’s attacking 4-3 defense ended up with some pretty high national rankings last season — seventh in total defense, seventh in pass defense, 17th in scoring — and sent two linebackers, a cornerback and defensive tackle to the NFL, where they are now fighting for jobs in preseason camps.

The veteran coach knows what his main challenges are.

“Just youth, and inexperience,” he said. “But that’s it. We’ll get them up to speed. They’re great kids. They want to be good. They’re working hard to learn the system.”

Shafer’s system calls upon defensive linemen to attack gaps and disrupt blocking schemes, allowing linebackers to make tackles and pressure the backfield. It needs defensive ends that can pressure, and cornerbacks with cover skills to keep quarterbacks from completing deep throws. It must have safeties who can quickly read and stop the run, but who don’t get fooled by play-action fakes.

Last year’s group had senior cornerbacks, a senior safety who started five games, three seniors who rotated at the defensive tackles — and a pair of senior linebackers who combined for one-quarter of the team’s total stops.

That’s a lot of experience, and a ton of leadership, to replace.

This year’s defense has veterans and potential stars at defensive end and safety, a mix of experience at cornerback and linebacker, and mostly new faces at defensive tackle.

But there’s reason to believe the group, which SU coaches feel is faster and every bit as athletic as the 2010 defense, could be pretty good — especially after it has time to gel under game conditions.

“It’s just a mater of getting repetitions and feeling comfortable with the techniques they’re learning, so they can quit thinking and just turn it loose,” Shafer said.

One thing the group has is speed. Players say that even the defensive tackles are faster this year, and that’s a good thing on a defense that runs and runs. That speed will have to offset a lack of size — particularly up front.

“This whole defense is a 4-3 defense that recruits athletes,” linebackers coach Dan Conley said about the size-versus-speed issue. “This defense is built to go out and recruit kids that can run, that can transition, change direction, and can hit. Our kids have to be passionate about running to the football.”

Defensive tackle

Sophomore Jason Bromley (6-3, 280) is the only returning player here with significant experience. The starting group lacks size. At the nose, junior college transfer Deon Goggins (6-1, 280) has earned a starting job after sitting out last season. The quick, athletic Goggins is somewhat small but has the ability to disrupt plays in opposing backfields. Junior Cory Boatman (6-1, 281) had been working at nose tackle all preseason but has moved behind Bromley at defensive tackle. True freshman Eric Crume (6-0, 332) is behind Goggins at the nose, with senior Ollie Haney (6-2, 290) and freshman Robert Welsh (6-2, 260) behind.

Defensive end

Veterans Chandler Jones (6-5, 265) and Mikhail Marinovich (6-5, 253) each came back bigger, stronger and more committed. Jones, a junior in eligibility, and senior Marinovich should provide valuable leadership. Senior Torrey Ball and junior Brandon Sharpe add experience behind Jones and Marinovich, but redshirt freshman Micah Robinson has impressed in camp and may push for playing time. True freshman Donnie Simmons is undersized at 230 pounds but has tremendous speed.

Linebacker

Sophomore Marquis Spruill is the only returning starter, moving to the middle where he played in prep school. Freshman Dyshawn Davis, who is still learning the position, will start at the weak side, and junior Dan Vaughan is at the strong side. Vaughan could be the glue in this group, as he knows all three linebacker positions. There’s no real experience behind this trio. Vaughan’s backup, is true freshman Cameron Lynch, and reserve middle linebacker Siriki Diabate is a junior-college transfer. Behind Davis is second-year walk-on Dom Anene, a junior.

Cornerback

Defensive captain Kevyn Scott, a redshirt senior, takes over at one corner position. A starter in 2009, Scott struggled through injuries last season and only played in six games. Sophomore Ri’Shard Anderson is at the other corner, at least until sophomore Keon Lyn’s shoulder injury heals. Behind Scott is true freshman Brandon Reddish. True freshmen Jaston George, who is battling a groin injury, and Ritchy Desir could redshirt.

Safety

Hard-hitting juniors Shamarko Thomas (strong safety) and Phillip Thomas (free safety) bring experience and passion. They were two of the top four tacklers on the Orange last season. Each was hurt in the preseason — Shamarko had a concussion, and Phillip had a fractured jaw. They’re backed by junior strong safety Olando Fisher and sophomore free safety Jeremi Wilkes, who can also play cornerback. True freshman Durell Eskridge grabbed everyone’s attention in the preseason and will push for playing time somewhere.